Thursday 27 October 2011 06.37 EDT
First published on Thursday 27 October 2011 06.37 EDT

Few crimes in recent years have captured the imagination quite so much as the murder in Perugia of Meredith Kercher. The beauty and kindness of the victim, the fresh faces of her alleged assassins, and their passion for sex and drugs, all set against the backdrop of one of Italy's most stunning cities, made this a story that was as captivating as it was tragic. Now that both Amanda Knox and Raffaele Sollecito have been acquitted of Kercher's murder, the story becomes in some ways even more fascinating, as no one knows quite what to believe any more. Many people remain convinced that the two are guilty.

John Follain is the Rome correspondent for the Sunday Times and has been following the case since it began. His book is a neutral retelling of events, from the British student's murder on the night of 1 November 2007 to that acquittal a few weeks ago on 3 October. Death in Perugia is not a first-person narrative, nor one that expresses an authorial opinion on the guilt or otherwise of those on trial. Perhaps because of this objectivity, it's a gripping read: a balanced, detailed account that allows the reader to respond to the central question: did they or didn't they?

It was immediately clear to detectives who attended the crime scene that a burglary had been faked. Windows had been smashed, but they were too high for a burglar and the broken glass was on top of, rather than underneath, the flat's ransacked contents. No burglar, detectives thought, would have locked Kercher's room. The flat's front door hadn't been forced. It looked as if someone on the inside had been involved in the murder, or had at least let in the murderer.

Attention turned to Kercher's American flatmate for many reasons: Amanda Knox had a scratch on her neck, and her behaviour as detectives watched her was bizarre in the extreme – constantly kissing and laughing with her Italian boyfriend, doing yoga in the police station, and snapping at one of Kercher's friends, who had expressed the hope that Meredith didn't suffer, with the retort: "She fucking bled to death."

As investigators looked more closely at Knox, she emerged as a narcissistic attention-seeker who was sexually adventurous but also jealous of Meredith Kercher's cheerful contentment. Knox knew, it seemed, no boundaries, leaving a vibrator in a transparent washbag and enjoying one-night stands. Detectives thought she was both sly and naive.

These character traits, however, were as nothing compared with the contradictions she got caught up in. At first she said she was there that fateful night; then that she wasn't. Pages of her diary were ripped out. Her phone, always on, had been switched off early that evening. She had used drugs. Most incredible of all, Knox claimed to have entered the flat the following morning, having found the front door open and blood in the bathroom, and rather than running outside and calling the police had gone straight ahead and had a shower without a second thought.

Her DNA was found on the handle of a knife that also had Kercher's DNA on its blade. That knife came from the kitchen of Knox's boyfriend, Sollecito. He, it emerged, was a habitual drug-user who liked knives and hardcore porn. His DNA was found on Kercher's bra clasp. He had lied about when he had used his computer, about the time of certain phone calls, and also about the time he'd eaten dinner.

A third man emerged as a suspect. Rudy Guede alleged that he had merely been making out with Meredith and was in the bathroom when he heard her screams from the other room. He tried, he said, to save her. Prosecutors didn't believe his story, especially when DNA evidence indicated a sexual encounter with Kercher – with, detectives thought, Knox and Sollecito involved as coercers. Various eyewitnesses came forward to place Guede, Knox and Sollecito at the scene of the crime, and the fact that the young lovers had bought bleach the following morning suggested they were trying to cover their tracks.

The evidence appeared overwhelming and all three were convicted. But earlier this month, Sollecito and Knox were acquitted. The lead prosecutor, Giuliano Mignini, had told the jury "you can't make a black boy pay for everyone", but that is how it now stands: only Guede, raised in Perugia, born in Ivory Coast, remains in prison. Doubts had been raised about the DNA evidence: the bra clasp had been found 46 days after the initial police search and contamination seemed a possibility. Witnesses were shown to be confused. Knox stopped laughing and clowning around in court. The prosecutor himself was described as a sex-obsessed conspiracy theorist. Now, as the prosecution appeal to overturn the acquittal, there will probably be another trial.

We will, of course, never really know what happened. Many remain convinced of Knox's guilt. "To my family," Meredith Kercher's father once said, "she is, unequivocally, culpable." One investigator said: "she's certainly not the first convict who claims she's innocent... My guess is that Amanda has convinced herself that she is." A prosecuting lawyer called her "a sorceress of deceit". Patrick Lumumba, the Congolese barman whom Knox falsely accused of the murder, said she was "the world's best actress". Others believe she was just a girl who, confused and in shock, behaved inappropriately but nothing more. Her lawyer said he would have been pleased to have her as a daughter.

It is a tribute to Follain and his publishers that this exhaustive account bears no sign of being a rush job. I would have liked the author to say who he thinks the guilty parties are, and to have stepped outside the story and told us why this case, more than any other, has so gripped the world's media (there have been 11 books so far and one film). But it's hard to imagine there will be a better book on the subject.

Tobias Jones's book about the murder of Elisa Claps, Blood on the Altar, will be published by Faber in spring